The interpolation of fast real time of parameter curved surface

Summary: The interpolation of fast real time that put forward curved surface of a kind of parameter is algorithmic. The triangle that this method changes by disperse is planar piece hand in a line to judge with the length that cuts plane all right and the feed inside computational interpolation cycle, reach initiative interpolation is nodded accordingly. This method shortened greatly parameter curved surface the time of real time interpolation, improved the efficiency of interpolation apparently. One, the interpolation leaving a line of numerical control system is in numerical control system, beard of traditional method of interpolation leaving a line has model through geometrical model system first, on this foundation, input the treatment craft information that concern through artificial interactive mode, repass generates relevant knife from line means file, the code instruction series of particular machine tool is made through the aftertreatment later. Can see from which, this kind of means leaving a line not only link is much, need to use up many mix artificially when machine, take up more soft hardware resource, and as a result of cutting tool method program and orbit photograph depart, the three-dimensional real time that implements cutting tool measure hard is exact compensation, make treatment and process designing need for many times to undertake, extended handling time. In the meantime, this process needs to undertake encode, decipher, deferent, memory and processing to mass data, increased the probability that make mistake greatly, cause adverse effect to the dependability of numerical control. To avoid to leave the inherent inadequacy of line process designing, people offerred the technology of real time interpolation, namely basis of numerical control system is machined the concerned information of curved surface, the knife that makes experience of have nothing to do with in real time orbit and the control statement that produce cutting tool motion, realize the control to machining a process from this. But this method is taller to interpolation technology requirement, ask the efficiency of interpolation algorithm is tall namely, because want to carry out real time interpolation, interpolation system must go the coordinate that next interpolation nod in the computation inside interpolation cycle, hand-in-hand travel interferes the processing that waits for relevant technology. Accordingly, at present machine tool of a lot of CNC can is opposite only undertake direct interpolation with circular arc point-blank, still cannot undertake real time interpolation to curved surface. To improve afore-mentioned conditions, we studied CNC Machining and curved surface carefully the relevant technology of real time interpolation, the real time interpolation that put forward curved surface of a kind of parameter is algorithmic, this algorithm train of thought is distinctive, shortened greatly parameter curved surface the time of real time interpolation, improved efficiency of real time interpolation significantly, make real time interpolation becomes free curved surface thereby likelihood. 2, the interpolation method of system of current CNC Machining basically divides the fundamental of interpolation it is two kinds big: One kind is pulse increment interpolation, namely interpolation of journey scalar quantity: Another kind of amount to occupies sampling interpolation, namely interpolation of time scalar quantity. Pulse increment interpolation is to use a pace to enter implement inside each pulse time into be apart from undertake interpolation as interpolation unit, this method is main and common in system of open loop numerical control, use at be being mixed point-blank the interpolation of circular arc, interpolation rate is average slower. And data sampling interpolation is the space that takes inside an interpolation cycle with cutting tool undertakes interpolation, this method can be used at the interpolation of relatively complex curve, and can realize fast interpolation. Considering pulse increment interpolation some of a few solid is not worth, this literary grace undertakes interpolation with data sampling method. The principle of this method is it is according to feed speed and interpolation cycle cipher out first inside an interpolation cycle cutting tool the feed on resultant velocity direction, later the value that measures according to real time when actual interpolation and the difference that are worth theoretically control each athletic rods to undertake interpolation through servo orgnaization. 3, real time interpolation uses the curved surface that the article puts forward the real time interpolation of parameter curved surface cut plane law. This method is divided into 3 parts. Be opposite above all disperse be undertakinged by treatment curved surface is changed, face its to undertake cut is handed in with a group of parallel next, beg a cut to cross a line, beg an initiative interpolation to nod, dot of initiative to these finally interpolation undertakes interfering handling generating a knife the disperse of course parameter curved surface changes the disperse to parameter curved surface, research is at present more. The article uses 4 forked trees to undertake to curved surface disperse is changed accommodative a triangle oneself, the treatment precision computation that asks according to curved surface above all namely gives the disperse precision that allows when disperse, undertake to curved surface according to this disperse precision again recursive fractionize, when among them child curved surface piece in recursive be decided to be in in fractionize process disperse precision allows farther to its fractionize stops when local evenness is inside precision, undertake all the time so all child curved surface piece it is local evenness till. Later, pass those who take local evenness child curved surface piece the center that 4 horn choose every stature curved surface piece translate into 4 triangles piece. Such, after be being changed through disperse, this parameter curved surface will have a series of trigonometry plane piece replace. Plane and curved surface undertake cut is handed in generate initiative interpolation the drop is current, type of knife course unripe figuration has wait for law of plane of parameter line law, cut and annulus to cut a way. Among them course of knife of cut plane law builds mass taller, the article uses reason cut plane law. Cut plane law uses a group to be taken commonly namely perpendicular go to what the curved surface that cut is machined uses them handing in a line to undertake relevant processing at the parallel plane of XY face in order to generate a knife the method of orbit. Because machine the disperse of the pace before curved surface is passed to change processing to already had a series of simple trigonometry plane piece composition, reason is mixed to plane of curved surface hand in a line to seek solution simpler, demand this plane and relevant trigonometry plane piece cross a line can. Nevertheless, what must explain here is, the disperse of the pace changes department argument Yu Xianglin before child curved surface piece fractionize administrative levels is different likelihood occurrence break and fold phenomenon, see figure. Of course this kind of phenomenon can undertake elimination through certain measure, but this will reduce the efficiency of disperse greatly and do not use for article place. The article needs this problem herein to make processing a bit only can. The triangle that is in when plane and break is planar generation crosses a line between a meeting when cut is handed in and break, the line segment AB with for instance medium attached drawing, and the same point that actually AB should be curved surface at 2 o'clock, as a result of,be only of disperse method be not perfected and arise. To eliminate this one appearance, the method that the article uses is fall in this kind of circumstance, take A, B the midpoint 2 o'clock is plane and interstitial place for C child curved surface piece attrib border node. Attached drawing disperse changes the crackle that appears in the process to pass the processing above, planar the kill that makes with the cut of curved surface will be a successive broken line. On this foundation, the means of real time interpolation of the article offers below. The place before be like is narrated, when interpolation of time scalar quantity, be in according to feed speed and interpolation cycle cipher out first underlying rate synthesizes this interpolation cycle the feed on direction, in the meantime, in process of specific interpolation curved surface, still must judge the machining error that undertakes with this feed whether interpolation can bring about treatment precision to allow more than right now, this process is handled relatively loaded down with trivial details, make interpolation efficiency is reduced apparently. For this, the article keeps away from this judgement process, and use directly above beg loses line segment each Duan Jin that go out to handle in an attempt to to solve the feed inside this interpolation cycle all right. Particular procedure is: Lose line segment to among them some, its length and the feed that press feed speed and interpolation cycle cipher out&Say here for standard feed ' undertake comparative, have undermentioned judgement: If broken line length is less than or be equal to standard feed to regard this interpolation cycle as the feed inside length of this broken line; Take broken line length otherwise / the feed that N regards this interpolation as cycle, among them: Length of N=INT(broken line / standard feed) + 1. Such, can beg an initiative interpolation expediently to nod, and the requirement that demands the initiative interpolation that go out to nod affirmative meeting to satisfy treatment precision so. Because this method avoided those who machine precision,examine and make interpolation efficiency rises greatly, this to real time interpolation it is very important. In the interference processing CNC Machining of knife course, because the radius of the cutting tool of the choice is more than the curvature radius of curved surface likely, such, if press above the knife that over osculatory point generates CNC Machining directly orbit, the cutting tool when the cutting tool when be being machined moves along this center can nod generation interfere in other. The knife that because this is actual,applies orbit is in what when generating, must undertake orbit is interfered reaching the designated position to examine. Actually, knife the interference of orbit examines is reach the designated position in CNC Machining the key that orbit makes one annulus, also be the one situation that compares difficulty and take time at the same time. Because the interpolation of the article is real time interpolation, so the requirement is in generate orbit while interference examines to generate knife of experience of have nothing to do with with real time orbit. The article uses promotion knife the law undertakes interfering examining, its train of thought is: In some interpolation dot, examine cutting tool whether the quadrangular face inside as umbriferous as this cutting tool area piece whether to interfere, if interference carries,rise cutting tool, till the quadrangular face inside its and umbriferous area piece hands-off till, right now, the center of this cutting tool interferes a knife to not have already dot, all contrail that nod without interference form knife of experience of have nothing to do with namely orbit. 4, the triangle that conclusion changes by disperse on the basis that the article changes in curved surface disperse is planar piece with what cut plane all right cut hands in a line to be judged directly and computational cutting tool is in the feed inside interpolation cycle, reach initiative interpolation is nodded accordingly. Such, shortened greatly interpolation time, improved the efficiency of interpolation apparently, the real time interpolation that is free curved surface laid solid foundation. In the meantime, this method also offerred new thinking for the interpolation method of free curved surface. CNC Milling